Apparatus for ascertaining and/or monitoring fill level and/or flow of a medium

• US 7,861,600 B2
• Filed: 07/29/2009
• Issued: 01/04/2011
• Est. Priority Date: 08/08/2008
• Status: Active Grant

• Current Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Mayer, Winfried, Mirbach, Michael
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US12/458,984
• Publication Number:
  US 20100031753A1
• Time in Patent Office: 524 Days
• Field of Search: 738/61, 732/90.R, 342/26.R
• US Class Current: 73/861
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: H01Q 1/225 used in level-measurement devices, e.g. for level gauge measurement
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H01Q 15/08 formed of solid dielectric material
• CPC Class Codes: H01Q 19/062 for focusing

Abstract

An apparatus for ascertaining and/or monitoring fill level and/or flow of a medium in a containment, including: at least one antenna, which radiates and/or receives high frequency signals according to a predetermined radiation characteristic along a main radiating axis in the direction of the surface of the medium; a control/evaluation unit, which evaluates the reflected high frequency signals and determines fill level on the basis of the travel time of the high frequency signals and/or flow on the basis of a Doppler frequency of the reflected high frequency signals; and at least one lens located between the antenna and the medium and having a first focal length in the direction of the antenna and a second focal length in the direction of the medium. A first focal point of the first focal length of the lens is so selected that the emitted high frequency signals of the antenna hit the lens within the lens aperture and that a second focal point of the second focal length lies in an opening region of the containment having an opening diameter that is smaller than the diameter of the lens aperture.

Claims

1. An apparatus for ascertaining and/or monitoring fill level and/or flow of a medium in a containment, comprising:

at least one antenna, which emits and/or receives high frequency signals with a predetermined radiation characteristic along a main radiation axis in the direction of the medium;

a control/evaluation unit, which evaluates the reflected high frequency signals and determines fill level on the basis of the travel time of the high frequency signals and/or flow on the basis of a Doppler frequency of the reflected high frequency signals; and

at least one lens provided between said at least one antenna and the medium and having a first focal length in the direction of said at least one antenna and a second focal length in the direction of the surface of the medium, wherein;

a first focal point of said first focal length is so selected, that the emitted high frequency signals of said at least one antenna hits said at least one lens within a lens aperture; and

a second focal point of said second focal length lies in an opening region of the containment having an opening diameter, which is smaller than the diameter of said lens aperture.

2. The apparatus as claimed in claim 1, wherein:

the containment is embodied as a bottle-like container having an opening in its neck region narrowed to a diameter defining said opening diameter; and

said second focal point of said second focal length of said at least one lens of the emitted high frequency signals reflected on the surface of the medium lies in this narrowed opening region.

3. The apparatus as claimed in claim 1, wherein:

the containment is embodied as a channel having a diameter defining said opening diameter in the opening region, in which said second focal point of said second focal length of the emitted high frequency signals reflected on the surface of the medium lies.

4. The apparatus as claimed in claim 1, wherein:

the main radiation axis of said at least one antenna is arranged offset relative to the optical axis of said at least one lens, so that the high frequency signals do not hit the surface of the medium perpendicularly and said control/evaluation unit ascertains the velocity of the flow of the medium on the basis of the frequency obtained by the Doppler effect due to the diffuse reflection of the high frequency signals on the surface of the medium.

5. The apparatus as claimed in claim 1, wherein:

said at least one antenna comprises a first antenna and at least a second antenna, whose main radiation axes are arranged at a skew angle relative to one another and/or with a different offset of the two main radiation axes of said first and said second antennas relative to the optical axis of said at least one lens; and

said control/evaluation unit ascertains consequently an unequivocal velocity of the flow of the medium from an averaging of the two frequencies obtained by the Doppler effect.

6. The apparatus as claimed in claim 1, wherein:

said second focal length lies in the order of magnitude of said first focal length of said at least one lens.

7. The apparatus as claimed in claim 1, wherein:

said at least one lens comprises a biconvex lens made of a dielectric material.

8. The apparatus as claimed in claim 1, wherein:

said at least one lens comprises a cylindrical lens made of a dielectric material.

9. The apparatus as claimed in claim 7, wherein:

said biconvex lens is made of a dielectric material blocking heat radiation or is coated with such a material blocking heat radiation and/or the surfaces of said biconvex lens is embodied by a structuring or a coating of an antireflection material.

10. The apparatus as claimed in claim 5, wherein:

a bistatic arrangement of said first antenna and said second antenna is so embodied that the main radiation directions hit in a location on the surface of the medium and thus radiated areas of said first focal point and said second focal point overlap.

11. The apparatus as claimed in claim 1, wherein:

as an aid for the directing of the main radiation directions of the antennas relative to the optical axis of said at least one lens, a marking of focal points on the surface of the medium is provided by means of an optically visible light point.